The prior method and devices do not allow continuous measurement of the gas SO2 during the heating cycle in an oxidizing atmosphere (oxidation cycle). Now, an analysis of the SO2 formed during oxidation of the organic matter is essential to determine the organic sulfur and mineral sulfur contents of said organic matter. Furthermore, this analysis can be carried out on the one hand directly from a first aliquot of an organic matter sample, and on the other hand with a second aliquot of the sample after it has first been subjected to a pyrolysis cycle. Comparison of these two measurements allows quantitative characterization of the total organic sulfur in a thermally labile fraction and a thermally refractory fraction.
All this information on the sulfur contents of a kerogen type material is important for knowledge of the production potentiality of a reservoir. For example, measurement of the SO2, by giving access to the organic and mineral sulfur contents of the kerogens, allows in fact to better characterize the various types of source rocks and their degree of thermal maturation, notably through determination of the labile and refractory sulfur contents. This measurement also allows to fine down the source rock oil correlations by comparison of the distribution of the sulfur and of its proportion in the oils and in the source rock pyrolysates. On a petroleum reservoir scale, the SO2 measurement performed from bitumen extracted from cores allows to make a diagnosis concerning their origin and their distribution in the reservoirs (gravity segregation, biodegradation, washout, thermal cracking, etc.). Differentiation between the SO2 of organic origin and the SO2 from pyrite allows to distinguish the bitumen and pyrobitumen levels, therefore the reservoir levels, from the source rock levels.